With a recent trend of miniaturization and weight lightening of electronic devices, miniaturization and weight lightening of batteries used therein as a power supply have also been required. Lithium secondary batteries are commercialized as batteries that are small, light, chargeable and dischargeable with high capacity, and used in portable electronic devices such as small video cameras, mobile phones and laptops, communication devices, etc.
Generally, a lithium secondary battery is formed with a positive electrode, a negative electrode, a separator and an electrolyte, and charge and discharge are possible due to lithium ions performing a role of transferring energy while travelling back and forth between both electrodes, for example lithium ions coming out of a positive electrode active material and being intercalated into a negative electrode active material, that is, carbon particles, by first charge, and deintercalated again during discharge.
Further, with the development of portable electronic devices, high capacity batteries have been continuously required, and research has been actively conducted on high capacity negative electrode materials such as tin, silicon or the like having significantly higher capacity per unit weight compared to carbon used currently as a negative electrode material. Among them, a negative electrode material using silicon has about 10 times higher capacity than a negative electrode material using carbon.
As a result, research has been conducted on a negative electrode material with high capacity using silicon in which there is no damage to the electrode even when lithium is intercalated and deintercalated repeatedly.